Radiotracer measurement of the volatilization of organic trace constituents from water

Abstract The mass-transfer coefficient for the volatilization of organic microconstituents from water can be determined by laboratory radiotracer experiments. Formulation and practical aspects are considered and illustrated by the example of a 5.10(-7) M solution of monochlorobenzene.     

Kinetics and mechanism of the anation of (αβ)-hydroxo(tetraethylenepentamine)cobalt(III) by thiosulfate, the base hydrolysis of the (sulfur-bonded) thiosulfato(tetraethylenepentamine)-cobalt(III) and photochemistry of oxygen and sulfur-bonded thiosulfato complexes

Summary The reaction of ()-(tetren)CoOH²⁺ with S₂O ₃ ^2- in the 7.25–8.28 pH range at 20–40 °C yielded S- (yellow) and O- (purple) bonded thiosulfato(tetren)cobalt(III) complexes, the former in larger quantities. The rate determining step is preceded by diffusion-controlled ion-pair [(tetren)CoOH²⁺,S₂O ₃ ^2- ] formation. Replacement of coordinated OH^- by S₂O ₃ ^2- is interpreted in terms of an internal conjugate base mechanism: (tetren)CoOH²⁺ (tetren-H)CoOH ₂ ²⁺ , the reactive amido conjugate base being generated by intramolecular proton transfer from the coordinated NH site.In acid medium the S-bonded (tetren)Co(S₂O₃)⁺ is highly stable to redox decomposition, in contrast to its pentaammine analogue. The complex however, undergoes base hydrolysis yielding the corresponding hydroxo complex. The rate and activation parameters for the base hydrolysis have been reported. Photolysis of O- and S-bonded isomers of [(tetren)CoS₂O₃]⁺ in acidic medium at 254 and 313 nm, respectively, yielded aquation products accompanied by some decomposition of S₂O ₃ ^2- .     

Determination of manganese in environmental samples (e.g. coal fly ash) by electrothermal AAS after its separation with a liquid chelating ion exchanger

An electrothermal atomic absorption spectrometric method is described for the determination of manganese in various coal fly ash samples after its separation with dissolved monothioxo--diketone as chelating ion exchanger. The detection limit is 1 ngml^-1. To study the accuracy of the method, a reference material of similar composition was analysed and recovery of spiked manganese was performed.